[PATCH AUTOSEL 5.3 035/203] rcu: Add destroy_work_on_stack() to match INIT_WORK_ONSTACK()

Sasha Levin
2019-09-22T19:38:33Z

From: "Paul E. McKenney" <paulmck@linux.ibm.com>

[ Upstream commit fbad01af8c3bb9618848abde8054ab7e0c2330fe ]

The synchronize_rcu_expedited() function has an INIT_WORK_ONSTACK(),
but lacks the corresponding destroy_work_on_stack(). This commit
therefore adds destroy_work_on_stack().

Reported-by: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
Acked-by: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
kernel/rcu/tree_exp.h | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/kernel/rcu/tree_exp.h b/kernel/rcu/tree_exp.h
index af7e7b9c86afa..513b403b683b7 100644
--- a/kernel/rcu/tree_exp.h
+++ b/kernel/rcu/tree_exp.h
@@ -792,6 +792,7 @@ static int rcu_print_task_exp_stall(struct rcu_node *rnp)
*/
void synchronize_rcu_expedited(void)
{
+ bool boottime = (rcu_scheduler_active == RCU_SCHEDULER_INIT);
struct rcu_exp_work rew;
struct rcu_node *rnp;
unsigned long s;
@@ -817,7 +818,7 @@ void synchronize_rcu_expedited(void)
return; /* Someone else did our work for us. */

/* Ensure that load happens before action based on it. */
- if (unlikely(rcu_scheduler_active == RCU_SCHEDULER_INIT)) {
+ if (unlikely(boottime)) {
/* Direct call during scheduler init and early_initcalls(). */
rcu_exp_sel_wait_wake(s);
} else {
@@ -835,5 +836,8 @@ void synchronize_rcu_expedited(void)

/* Let the next expedited grace period start. */
mutex_unlock(&rcu_state.exp_mutex);
+
+ if (likely(!boottime))
+ destroy_work_on_stack(&rew.rew_work);
}
EXPORT_SYMBOL_GPL(synchronize_rcu_expedited);
--
2.20.1